A principal technique in image recognition is a template matching (for example, see Non-patent Reference 1). The template matching is a method for preparing, in advance, image windows (templates) each having a various specific shape, applying one of the templates to a target image to be recognized, and testing whether or not a matching object is present in the target image.
More specifically, as shown in FIG. 1, a conventional image recognition device 100 includes an image input unit 101 which obtains the target image, a database (database for recognition) 103 exclusive for image recognition, a recognition unit 102 which performs recognition processing by verifying the target image obtained by the image input unit 101 with the templates in the database for recognition, and a presentation unit 104 which outputs the result of recognition. The conventional image recognition device like this has been proved successful in face recognition according to such template matching.
Non-patent Reference 1: D. A. Forsyth and J. Ponce, “COMPUTER VISION: A Modern Approach”, Clauses 22 and 24.3